The trio grey dirt surface are hard wearing, but can suffer erosion after some heavy rain events.
Basic repair involves:
1. Scraping sediment in collection zones into small piles. This should be mostly dry.
2. Wetting down the surface for repair
3. Throwing dry sediment across the surface.
4. Brushing into a smooth layer.
5. Wetting lightly and riding.
An example is shown below.
This follows the grey dirt maintenance method described for the Dirt Jumps in another post.
Periodically, a more substantial repair using plate compaction should be considered.